// Return true if we successfully sent an ARP request, false otherwise
bool IPv4Handler::resolveMac(SwitchState* state, IPAddressV4 dest) {
// need to find out our own IP and MAC addresses so that we can send the
// ARP request out. Since the request will be broadcast, there is no need to
// worry about which port to send the packet out.
// TODO: assume vrf 0 now
auto routeTable = state->getRouteTables()->getRouteTableIf(RouterID(0));
if (!routeTable) {
throw FbossError("No routing tables found");
}
auto route = routeTable->getRibV4()->longestMatch(dest);
if (!route || !route->isResolved()) {
// No way to reach dest
return false;
}
auto intfs = state->getInterfaces();
auto nhs = route->getForwardInfo().getNexthops();
for (auto nh : nhs) {
auto intf = intfs->getInterfaceIf(nh.intf);
if (intf) {
auto source = intf->getAddressToReach(nh.nexthop)->first.asV4();
auto target = route->isConnected() ? dest : nh.nexthop.asV4();
if (source == target) {
// This packet is for us. Don't send ARP requess for our own IP.
continue;
}
auto vlanID = intf->getVlanID();
auto vlan = state->getVlans()->getVlanIf(vlanID);
if (vlan) {
auto entry = vlan->getArpTable()->getEntryIf(target);
if (entry == nullptr) {
// No entry in ARP table, send ARP request
auto mac = intf->getMac();
ArpHandler::sendArpRequest(sw_, vlanID, mac, source, target);
// Notify the updater that we sent an arp request
sw_->getNeighborUpdater()->sentArpRequest(vlanID, target);
} else {
VLOG(4) << "not sending arp for " << target.str() << ", "
<< ((entry->isPending()) ? "pending " : "")
<< "entry already exists";
}
}
}
}
return true;
}
void UnresolvedNhopsProber::timeoutExpired() noexcept {
std::lock_guard<std::mutex> g(lock_);
auto state = sw_->getState();
for (const auto& ridAndNhopsRefCounts : nhops2RouteCount_) {
for (const auto& nhopAndRefCount : ridAndNhopsRefCounts.second) {
const auto& nhop = nhopAndRefCount.first;
auto intf = state->getInterfaces()->getInterfaceIf(nhop.intf());
if (!intf) {
continue; // interface got unconfigured
}
// Probe all nexthops for which either don't have a L2 entry
// or the entry is not resolved (port == 0). Note that we do
// not exclude pending entries here since in case of recursive
// routes we might get packets with destination set to prefix
// that needs to be resolved recursively. In ARP and NDP code
// we do not do route lookup when deciding to send ARP/NDP requests.
// So we would only try to ARP/NDP for the destination if it
// is in one of the interface subnets (which it won't be else
// we won't have needed recursive resolution). So ARP/NDP for
// all unresolved next hops. We could also consider doing route
// lookups in ARP/NDP code, but by probing all unresolved next
// hops we effectively do the same thing, since the next hops
// probed come from after the route was (recursively) resolved.
auto vlan = state->getVlans()->getVlanIf(intf->getVlanID());
CHECK(vlan); // must have vlan for configrued inteface
if (nhop.addr().isV4()) {
auto nhop4 = nhop.addr().asV4();
auto arpEntry = vlan->getArpTable()->getEntryIf(nhop4);
if (!arpEntry || arpEntry->getPort() == PortID(0)) {
VLOG(3) <<" Sending probe for unresolved next hop: " << nhop4;
ArpHandler::sendArpRequest(sw_, vlan, nhop4);
}
} else {
auto nhop6 = nhop.addr().asV6();
auto ndpEntry = vlan->getNdpTable()->getEntryIf(nhop6);
if (!ndpEntry || ndpEntry->getPort() == PortID(0)) {
VLOG(3) <<" Sending probe for unresolved next hop: " << nhop6;
IPv6Handler::sendNeighborSolicitation(sw_, nhop6, vlan);
}
}
}
}
scheduleTimeout(interval_);
}
